The present invention relates to a process for the preparation of 3-hydroxymethyl tetrahydrofuran. The present invention particularly relates to a catalytic process for the preparation of 3-hydroxymethyl tetrahydrofuran with hydroformylation as one of the key steps.
3-hydroxymethyl tetrahydrofuran is an important intermediate in the synthesis of drugs and pesticides. The guanidine derivatives derivable from 3-hydroxymethyl tetrahydrofuran have assumed greater significance as pesticides in recent years. (JP 07 173,157; U.S. Pat. No. 5,382,596; JP 08 245,323; JP 08 245,32; JP 08 259,568, JP 08, 259,554, JP 08 259,553; JP08 269,035; JP 08 291,009; JP 08 269,034; JP 08 295,684; JP 08 291,169; JP 08 291,171; JP 08 311,063; U.S. Pat. No. 5,585,397; JP 09 12,565; EP 0649845).
In the art, it is known to prepare 3-hydroxymethyl tetrahydrofuran by dehydration of 2-hydroxymethyl-1,4-butanediol in the presence of phosphoric acid. 2-hydroxymethyl-1,4-butanediol was prepared by reduction of 2-carboethoxy diethyl succinate using LiBH4 [C.R.Acad. Sci., Paris, Ser. C264(10), 894-6(1967) (Fr)]. This procedure has the disadvantage of using large quantities of LiBH4 to effect reduction of the esters to the corresponding alcohol. Since 2-hydroxymethyl-1,4-butanediol is highly soluble in water, this method also has the disadvantage of requiring isolation of the triol from aqueous solutions during work up. Recently in 1997 a process for the preparation of 3-hydroxymethyl tetrahydrofuran was reported by cyclocondensation of 2-bydroxymethyl-1,4-butanediol using para toluenesulphonic Acid, [JP 08,291,159, CA 126:74732], This process has the disadvantage of prior separation of soluble para toluene sulphonic acid from the reaction mixture, before 2-bydroxymethyl tetrahydrofuran is isolated either by solvent extraction and/or distillation. The reactions involved in procedures mentioned above are all stiochiometric reactions.
In view of these disadvantages it is felt highly desirable to develop a practical process for the preparation of 3-hydroxymethyl tetrahydrofuran. It is also felt necessary to develop a process, in which salt generation is kept at minimum, to make it environmentally friendly. The process thus developed will have the advantage of being catalytic and free of salt generation.
The main object of the present invention is to provide a process for the preparation of 3-hydroxymethyl tetrahydrofuran of the formula IV starting from cyclohexanone and but-2-ene-1,4-diol.
It is another object of the invention to provide a process for the preparation of 3-hydroxymethyl tetrahydrofuran wherein salt generation is minimised thereby making the process more environmentally friendly.
Accordingly the present invention provides a process for the preparation of 3-hydroxymethyl tetrahydrofuran of the formula IV, 
said process comprising reacting 9-hydroxymethyl-7,12-dioxaspiro dodecane of the formula III 
with an alcohol at a temperature in the range of 100-140xc2x0 C. for a time period in the range of 1-4 hr. in the presence of an acid catalyst and recovering the 3-hydroxymethyl tetrahydrofuran.
In one embodiment of the invention the alcohol used contains 1 to 4 carbon atoms and is selected from the group consisting of methanol, ethanol, propanol and butanol.
In another embodiment of the invention the acid catalyst used comprises a heterogeneous acid catalysts.
In a further embodiment of the invention, the acid catalyst used is selected from the group consisting of amberlyst-15, Montmorillonite K-10 and Sulphonated Nitro Coal Acid (SNCA).
The process of the present invention is detailed below.
7,12-dioxaspiro[5,6]dodec-9-ene of the formula I obtained by reacting cyclohexanone with but-2-ene-1,4-diol was hydroformylated using Rhodium catalyst to give 9-formyl-7,12-dioxaspiro[5,6]dodecane of the formula II. 9-hydroxymethyl-7,12-dioxaspiro[5,6]dodecane of the formula III obtained by reduction of formyl group was subjected to simultaneous transketalisation and cyclodehydration to give 3-hydroxymethyl tetrahydrofuran of the formula IV in the presence of a heterogeneous acid catalyst. The product 3-hydroxymethyl tetrahydrofuran was distilled after filtration of the catalyst. The entire process of the reaction is detailed in the reaction scheme below: 
U.S. Pat. No. 5,864,046 granted to Pardhasaradhi et al discloses the preparation of 9-hydroxymethyl-7,12-dioxaspiro[5,6]dodecane of the formula III via hydroformylation followed by reduction starting from cyclohexanone and but-2-ene-1,4-diol.